For MEMS devices, packaging has been a challenging topic to improve its quality and stability, such as temperature coefficient of offset (TCO) or zero-motion offset (ZMO) for motion sensors like accelerometers and gyroscopes, etc. These related issues are caused by the packaging stress. A large TCO or ZMO makes it difficult to design a stable MEMS device over a wide range of temperature or in various applications.
In some MEMS packaging with molding compound to encapsulate the MEMS device, a big difference in Young's modulus values and coefficients of thermal expansion (CTE) between different materials will induce a large residual thermal stress on the MEMS device and cause a measurement TCO or ZMO issue, which is also a function of ambient temperature and humidity. This stress-induced offset issue is undesirable for MEMS devices.